Hi, thank you for reaching out. We are in the process of shuffling some data around, and nsc_dr1 is one of the datasets. We neglected to temporarily remove it from the TAP schema, so it appears available. Fixing right now.
In the meantime, unless you absolutely must use DR1, we recommend you query nsc_dr2 instead, as it supersedes DR1.
DR1 should become available again in a few days though.
Robert, for the DL team